In the art of seismic exploration, a primary purpose is to create an impulse or series of impulses that can be recorded to refl9ct the environment through which the impulses pass. In the instance of offshore seismic exploration, or in the instance of a borehole such as a well, the liquid environment is utilized as part of the sound creating and transmitting medium.
Different forms of underwater acoustic sources, often referred to as seismic guns, are known and widely used by the petroleum industry. These devices cover both the explosion type, and the implosion type. Functionally, the surrounding water can be caused to explode outwardly to create an acoustic discharge. Similarly, a rapidly flowing water mass into an evacuated area, can effect a sound producing, readable impulse.
In the instance of well boreholes, or in a deep body of water, it is necessary to convey or direct the impulse creating medium to the submerged gun whereby to trigger the latter. It is therefore necessary to provide a sufficient length of tubing, cable or similar conduit through which the power medium, normally water or a hydraulic fluid, travels.
In the disclosed apparatus, the acoustic sound source is particularly adapted for use in a well bore wherein an amount of water has accumulated for a considerable depth. The acoustic apparatus is provided with at least one implosion chamber. The latter is adapted to be evacuated of water, and thereafter to admit a rapid inflow of the surrounding water thereby to create conditions for the implosion.
The implosion chamber slidably receives a piston assembly in a manner that the water can be displaced from said chamber with each piston stroke. At the end of the piston travel, water will be rapidly released into the evacuated implosion chamber, causing the latter to rapidly fill.
Subsequent movement of the actuating piston to its retracted position is accomplished through a check valve which permits trapped water to be discharged from the implosion chamber as the piston moves.
As herein shown, the novel apparatus comprises an elongated body having a pair of oppositely positioned implosion chambers. The rate of acoustic implosions can thereby be doubled. This is achieved by use of a double ended piston rod, each piston head being registered in one of the oppositely positioned implosion chambers.
It is therefore an object of the invention to provide an acoustic energy apparatus of the type contemplated which is adapted to function in an underwater environment.
A further object is to provide an acoustic energy gun of the type wherein the surrounding liquid medium such as water, is used as the impulse creating medium by virtue of an implosion action.
A still further object is to provide an underwater acoustic energy source which is powered by a hydraulic pump or the like positioned remotely from the apparatus, whereby to establish a continuous series of recordable sounds as a result of sequential implosions.